In this retrospective study, clinical data including clinical manifestations, routine blood tests, chest radiographic imaging from 77 severe cases of SARS treated with integrated Chinese and Western medicine were collected and statistically analyzed. Twenty-nine (37.6%) patients were admitted to the intensive care unit, non-invasive ventilation was used in 40 (51.9%) cases, and invasive ventilatory procedure was performed in eight (10.3%) cases. Seventy (90.9%) patients were clinically cured and seven (9.0%) died. The duration of defervescence was 8.3 +/- 5.0 days after admission. In the early stage, normal leucocyte count was seen in 46 (75.4%) of the 61 patients tested, decreased leucocyte count in 13 (21.3%) and elevated leucocyte count in only two (3.2%) cases. A decreased lymphocyte count was also seen in 23 (37.7%) cases of the 61 patients tested on admission, and by day 14, the number of patients with decreased lymphocyte count (1.11 +/- 0.66 x 10(9)) increased to 32 (47.7%) in 67 cases examined. Neutral granulocyte count was normal or decreased in 58 (95.0%) patients on admission, but elevated from the 7th day onward and peaked on day 21 in 32 (65.3%) of the 49 cases tested. All of the blood abnormalities returned to normal in the convalescent stage. Twenty-nine (37.6%) of the 77 severe cases of SARS patients demonstrated an extensive lung involvement. In comparison with the non-severe SARS cases, this group of patients showed significantly more pneumonic air-space opacities and ground glass-like changes on the chest radiographs (p < 0.05, chi2 test). The role Chinese medicine played in the treatment of SARS was discussed.